Nice work. Just FYI for anybody else - it adds an icon to status bar (if that's what it's called? - top right icons). I thought it was going to open an app window and didn't notice the icon, so thought it wasn't working. (In hindsight, it's clear from screenshots in app store).
I think it's called the menu bar, and apps that don't open windows (with an icon in the menu bar) are known as "menu bar apps". Until recently, these were a PITA to implement with Apple's SDK. Thankfully they provided API support sometime I think starting with macOS 13... before that it was pretty kludgy.
